diff --git a/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c b/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c
index 4127988d62..5f6802e6d2 100644
--- a/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c
+++ b/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c
@@ -60,7 +60,8 @@ void NVIC_SetVector(IRQn_Type IRQn, uint32_t vector) {
     
     // Copy and switch to dynamic vectors if first time called
     if((LPC_SYSCON->SYSMEMREMAP & 0x3) != 0x1) {     
-      uint32_t *old_vectors = (uint32_t *)0;         // FLASH vectors are at 0x0
+      // Add volatile qualifier to avoid armclang aggressive optimization
+      volatile uint32_t *old_vectors = (uint32_t *)0;         // FLASH vectors are at 0x0
       for(i = 0; i < NVIC_NUM_VECTORS; i++) {    
             vectors[i] = old_vectors[i];
         }